“All sides must join in the effort to fully investigate all human rights violations and acts of violence,” the document by Steinmeier, Fabius and Sikorski, who are holding a three-party meeting in the German city of Weimar, says.

“We encourage the Ukrainian leadership to accelerate the ongoing process of disarmament, re-establish the state monopoly on the use of force as well as distance itself from extremist groups,” the statement says.

“As witnesses of the 21 February agreement [between Ukrainian President Viktor Yanukovich and the opposition], we encourage the Ukrainian authorities to ensure that key principles contained in the agreement become part of Ukrainian policy,” the ministers said. “This would also contribute to the implementation of the Association Agreement.”

The top diplomats also called on the current Kiev authorities “to reach out towards all regions of Ukraine and to ensure the representative nature and inclusiveness of governmental structures.”

“Presidential elections must take place on May 25, be thoroughly prepared and be free and fair. In the same vein we would welcome a timetable for the process leading to a constitutional reform,” the statement said.

Anti-government protests started in Ukraine in November 2013 when the country suspended the signing of an association agreement with the EU in favor of closer ties with Russia. The protests often turned violent and eventually ended with a coup in February 2014.

Activists from the Right Sector, a Ukrainian radical group, were reportedly involved in deadly clashes with police in Ukraine’s riots.

After Yanukovich left Ukraine citing security concerns, the Ukrainian parliament appointed its speaker, Alexander Turchinov, as acting president of the country and approved a new government led by Arseny Yatsenyuk, the leader of the parliamentary faction of the Batkivshchina party. The Verkhovna Rada also set early presidential elections for May 25.

The Ukrainian crisis deepened when the Republic of Crimea signed a treaty with the Russian Federation to become its constituent member on March 18 after a referendum two days earlier in which most Crimeans voted to secede from Ukraine and join Russia.

Hundreds of activists from the Right Sector on March 27 gathered in front of the building of the Ukrainian unicameral parliament, the Verkhovna Rada, in Kiev. Activists stormed the building, smashing windows in it and causing lawmakers to leave. The radicals later retreated.

The storm followed the killing of Right Sector coordinator, ultranationalist Alexander Muzychko (Sashko Bily), wanted by Russia for torture and killings of Russian soldiers in the Russian North Caucasus republic of Chechnya in 1994-2000, in a special operation by Ukrainian law enforcers in western Ukraine on March 25.